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Title: Mixed-Metal, Structural, and Substitution Effects of Polyoxometalates on Electrochemical Behavior in a Redox Flow Battery

A pair of redox flow batteries containing polyoxometalates was tested as part of an ongoing program in stationary energy storage. The iron-containing dimer, (SiFe3W9(OH)3O34)2(OH)311-, cycled between (SiFe3W9(OH)3O34)2(OH)311-/(SiFe3W9(OH)3O34)2(OH)314-and (SiFe3W9(OH)3O34)2(OH)317-/(SiFe3W9(OH)3O34)2(OH)314- for the positive and negative electrode, respectively. This compound demonstrated a coulombic efficiency of 83% after 20 cycles with an electrochemical yield (measured discharge capacity as a percentage of theoretical capacity) of 55%. Cyclic voltammetry on the Lindqvist ion, cis-V2W4O194-, showed quasi-reversible vanadium electrochemistry, but tungsten reduction was mostly irreversible. In a flow cell configuration, cis-V2W4O194-had a coulombic efficiency of 45% (for a two-electron process) and an electrochemical yield of 16% after 20 cycles. The poor performance of cis-V2W4O194-was attributed primarily to its higher charge density. Collectively, the results showed that both polyoxometalate size and charge density are both important parameters to consider in battery material performance.
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Sandia National Laboratories
  2. Ames Laboratory
Publication Date:
OSTI Identifier:
Report Number(s):
IS-J 8443
Journal ID: ISSN 0013-4686
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Electrochimica Acta; Journal Volume: 138
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; IRON; VANADIUM; MAGNETIC SUSCEPTIBILITY Flow battery; Polyoxometalates; Iron; Vanadium; Magnetic susceptibility